Troubleshooting Hydraulic Trailer Brakes Not Working Properly Even When Lines are Free of Air

Question:

We have a 2002 Kimberley Kamper trailer single axle. We have installed a new master cylinder, serviced brake callipers, but we now have trouble bleeding the brakes. There is no air coming out of the lines. I know it is good no air bubbles are coming out, but the brakes don’t stay hard. They go soft again.This means the hydraulic brakes are not working. We think there might be a leak somewhere, but have no idea where. May be you can give us some ideas where to look for leaks. I hope this is enough information for you to be able to give us an answer on what we might be doing wrong or what other problem it could be. Regards

asked by: Rudi

Expert Reply:

The most likely place for brake fluid to be leaking out of your hydraulic brake system is at the fittings or master cylinder. To check the fittings, chock the trailer wheels and back up the trailer so that the brakes engage. With the actuator engaged and pushing brake fluid through to the brakes, check to see if fluid is leaking out at any of the fittings. If you find any leaks at the fittings you will want to replace the fitting.

If you find that none of the fittings are leaking, it could be that the brakes are not properly engaging and that additional components in the actuator need to be replaced, such as the actuator shock or push rod. If the shock is bad, the coupler may not be fully engaging consistently and not apply enough pressure to the brakes.

The actuator shock and push rod are components specific to certain brand actuators. You will want to know the make and model number of the actuator to find the correct replacement parts.

expert reply by: Victoria B